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Research Article pubs.acs.org/journal/ascecg

Zirconium Doped Ceria Nanoparticles: An Efficient and Reusable Catalyst for a Green Multicomponent Synthesis of Novel Phenyldiazenyl−Chromene Derivatives Using Aqueous Medium P. Sagar Vijay Kumar,† L. Suresh,† T. Vinodkumar,† Benjaram. M. Reddy,‡ and G. V. P. Chandramouli*,† †

Department of Chemistry, National Institute of Technology, Warangal, 506 004, Telangana, India Inorganic and Physical Chemistry Division, CSIR−Indian Institute of Chemical Technology, Uppal Road, Hyderabad, 500 007, India

‡

S Supporting Information *

ABSTRACT: Zirconium doped ceria nanoparticles are found to be efficient heterogeneous catalysts for the multicomponent reaction of 1,3-dicarbonyl compounds with 4-hydroxy-3methoxy-5-(substituted-phenyl-diazenyl) benzaldehydes and malononitrile to yield the corresponding 2-amino-4-(4hydroxy-3-methoxy-5-(substituted-phenyl-diazenyl)-chromene-3-carbonitrile derivatives in water medium. The results show that nanosized CeO2−ZrO2 is a potential catalytic material for synthesis of title compounds in high yields. The used catalyst was recovered and reused several times without significant loss of catalytic activity, which is an essential parameter of green synthesis. The formation, size, and oxidation state of the metal ions present in the material is confirmed by powdered X-ray diffraction, transmission electron spectroscopy, and X-ray photoelectron spectroscopy techniques. KEYWORDS: Zirconium doped ceria nanoparticles, Multicomponent reaction, Phenyldiazenyl−chromene, Aqueous medium

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INTRODUCTION Green chemistry has become an essential inspiration for organic chemists to improve environmentally benign reagents and conditions for synthesis of organic compounds.1 It is well established fact that the sustainability of green chemistry greatly depends on (i) the use of benign solvents or solvent-free conditions, (ii) the development of less toxic and promising reagents/catalysts, (iii) the design of cost-effective and reliable methodologies, and (iv) development of reusable catalysts. In view of these, the development of nano metal oxide catalysts has drawn much attention due to their operational simplicity, environmental friendliness, easy separation procedure, economic efficiency, and recyclability.2,3 In recent years, zirconium doped ceria catalysts have been proposed as promising materials for energy and environmentally related applications such as catalysts, fuel cells, gas sensors, generation of solar fuels, oxidation of carbon monoxide, soot, etc. All these applications are due to the presence of more oxygen defects, high reduction properties, good acid−base properties, etc.4−6 In addition to this, the use of water as a promising solvent for organic reactions has been established in considerable interest due to its green identifications such as low cost and easy availability. Besides, the factors like network of hydrogen bonds, high specific heat capacity, large surface tension, high polarity, and high cohesive energy have been highlighted as some of the characteristic properties of water that can intensely influence the organic conversions in this medium.7 © XXXX American Chemical Society

Multicomponent reactions (MCRs) have drawn great interest in enjoying an unresolved status in modern organic synthesis and medicinal chemistry. Multicomponent reaction protocols offer incredible advantages such as high selectivity, high yields and structural diversity of drug scafolds.8,9 Theoretically, MCRs are potential candidates for use of water as solvent since the multiple hydrophobic reactants are carried in closer proximity due to hydrophobic interactions.10 The chromene moiety often appears as an important structural component in compounds exhibiting antimicrobial,11 anticancer,12 antitubercular,13 antioxidant,14 antiproliferation,15 and antimalarial16 activities. On the other hand, azo compounds are highly significant as synthetic dyes. They also have diverse applications in several fields such as medicinal chemistry and dyeing textile fiber.17,18 In recent years, azo compounds have been intensively studied, due their activities such as antifungal agents,19 anticancer agents,20 tyrosinase inhibitors,21 and vesicular glutamate transporter inhibitors.22 Therefore, synthesis of an azo group containing chromene derivatives using green protocols attracted significant attention. In continuation of our efforts toward the development of novel heterocyclic compounds using green protocols23,24 herein, we report a facile synthesis of 2-amino-4-(4-hydroxy-3-methoxy-5-(substitutedReceived: January 10, 2016 Revised: February 17, 2016

A

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Figure 1. (a) Powder X-ray diffraction patterns of zirconium doped ceria nanoparticles calcined at 773 and 1073 K. (b) Transmission electron microscopy image of zirconium doped ceria nanoparticles calcined at 773 K.

To identify the chemical states of the dopant and the host ions on the surface of the CeO2−ZrO2 material XPS study was carried out and shown in Figure 2. The Ce 3d XP spectrum of CeO2−ZrO2, shown in Figure 2a, suggests the coexistence of Ce3+ and Ce4+ and characterized by two series of peaks: 3d3/2 and 3d5/2 labeled as u and v, respectively. The peaks designated as u, u″, u‴ and v, v″, v‴ can be assigned to Ce4+ while the peaks u′ and v′ belonging to Ce3+.25 The O 1s spectrum of CeO2−ZrO2 material is illustrated in Figure 2b. The peak centered at 530.3 eV is related to the lattice oxygen and the peak located at 532.3 eV is ascribed to adsorbed oxygen (O−, O2−, or OH−).26 Zr 3d XP spectrum of prepared CeO2−ZrO2 nanomaterial is shown in Figure 2c, reveals two peaks at 182.4 and 184.7 eV corresponding to Zr 3d5/2 and Zr 3d3/2 respectively, which are assigned to +4 oxidation state of the zirconium.27 From the XPS studies, it is clear that on the surface of the CeO2−ZrO2 material Ce exists in the 3+ and 4+ states and Zr in 4+ states along with the presence of two types of oxygen (lattice oxygen and adsorbed oxygen). To show the merits of CeO2−ZrO2 nanoparticles in organic synthesis, we applied this catalyst for multicomponent reaction. A green protocol was used for the synthesis of 2-amino-4-(4hydroxy-3-methoxy-5-(substituted-phenyl-diazenyl)-chromene3-carbonitrile derivatives 4aa−bd via a multicomponent approach from the reaction of 1,3-dicarbonyl compounds (1a−e, 1 mmol), 4-hydroxy-3-methoxy-5-(substituted-phenyldiazenyl)-benzaldehydes (2a−f, 1 mmol) and malononitrile (3, 1 mmol) in the presence of CeO2−ZrO2 nanoparticles (NPs) as a catalyst in aqueous medium at room temperature. Initial studies were carried out by reaction between 4-hydroxy-6methyl-2H-chromene-2-one 1a, 4-hydroxy-3-methoxy-5-((2nitrophenyl)-diazenyl)-benzaldehyde 2c, and malononitrile 3 as a model reaction in different solvents and catalysts. We have applied wide range of solvents such as methanol, ethanol, water, acetonitrile, and dioxane (Table 1, entries 1−5). Water was proved to be the solvent of choice and improved for all imminent studies. To optimize the reaction conditions in terms of catalyst above model reaction was performed using different catalysts like KOH, triethylamine, piperidine, H2SO4, acetic acid (Table 1, entries 6−10) including nano catalysts i.e.,

phenyldiazenyl)-pyran-3-carbonitrile derivatives. To the best of our knowledge, for the first time, an ecofriendly process was developed for the synthesis of novel 2-amino-4-(4-hydroxy-3methoxy-5-(substituted-phenyldiazenyl)-pyran-3-carbonitrile scaffold from 1,3-dicarbonyl compounds, 4-hydroxy-3-methoxy5-(substituted-phenyldiazenyl) benzaldehydes, and malononitrile in the presence of zirconium doped ceria nanoparticles (CeO2−ZrO2). The used material was prepared by coprecipitation method and characterized using powdered-X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) techniques.

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RESULTS AND DISCUSSIONS The CeO2−ZrO2 (CZ 1:1 mol ratio based on oxides) solid solution was synthesized by a modified coprecipitation method using appropriate amounts of the corresponding Ce(NO3)3· 6H2O (Aldrich, AR grade) and ZrO(NO3)2·xH2O (Fluka, AR grade) precursors. The desired amounts of the precursors were dissolved separately in double-distilled water under mild stirring conditions and mixed together. Dilute aqueous ammonia solution was added dropwise over a period until the pH of the solution reached ∼8.5. The resulting pale yellow colored slurry was decanted, filtered, and washed several times with double distilled water until it was free from anion impurities. The obtained precipitate was oven-dried at 393 K for 12 h and calcined at 773 and 1073 K for 5 h at a heating rate of 5 K min−1 in an air atmosphere. Figure 1a shows the X-ray diffractograms of the zirconium doped ceria catalysts (CeO2−ZrO2) calcined at 773 and 1073 K. The main peaks (111), (200), (220), and (311) observed in this figure correspond to the typical cubic structure of ceria. No characterization peaks related to zirconium oxide were observed which confirm the formation of solid solution. The average crystallite size of CeO2−ZrO2 materials is calculated by using the most intense peaks such as (111), (220), and (311) with the help of Sherrer equation, and the obtained value is around 4.7 nm at 773 K and 5.5 nm at 1073 K. From Figure 1a, it is apparent that, the material is stable even at 1073 K. The TEM image of the CeO2−ZrO2 material (Figure 1b) reveals that the average particle size of the prepared material is 4−6 nm, which is in agreement with the XRD results. B

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low temperature (room temperature) improved the reaction yields. All these optimized conditions were then applied for all further experiments. Typically, a mixture of 1,3-dicarbonyl compounds (1 mmol), (substituted-phenyl-diazenyl)-benzaldehydes (1 mmol), malononitrile (1 mmol), and 20 mol % of nano-CeO2−ZrO2 in 5 mL of water at room temperature for 3 h, which afforded a library of 2-amino-4-(4-hydroxy-3-methoxy5-(substituted-phenyldiazenyl)-chromene-3-carbonitrile derivatives 4aa−bd in good to excellent yields (79−93%). To estimate the scope and generality of the procedure, 4-hydroxy3-methoxy-5-(substituted-phenyl)diazenyl)-benzaldehydes like 4-hydroxy-3-methoxy-5-(phenyldiazenyl)-benzaldehyde (2a), 4-hydroxy-3-methoxy-5-(p-tolyldiazenyl)-benzaldehyde (2b), 4-hydroxy-3-methoxy-5-((2-nitrophenyl)diazenyl)-benzaldehyde (2c), 4-hydroxy-3-methoxy-5-((3-nitrophenyl)diazenyl)benzaldehyde (2d), 4-hydroxy-3-methoxy-5-((4-nitrophenyl)diazenyl)-benzaldehyde (2e), and 3-((3-fluoro-4morpholinophenyl)diazenyl)-4-hydroxy-5-methoxybenzaldehyde (2f) having both electron-donating and electron-withdrawing groups were reacted with 1,3-dicarbonyl compounds like 4-hydroxy-6-methyl-2H-chromene-2-one (1a), 4-hydroxycoumarin (1b), 2-hydroxy-1,4-naphthoquinone (1c), 5,5dimethyl-1,3-cyclohexanedione (1d), and 1,3-cyclohexanedione (1e) and malononitrile (3) under optimized conditions, and results are summarized in Table 2. To show the significance of nanosized CeO2−ZrO2 catalyst, its reusability was tested upon the synthesis of compound 4ac with 4-hydroxy-6-methyl-2H-chromene-2-one 1a, 4-hydroxy-3methoxy-5-((2-nitrophenyl)diazenyl)benzaldehyde 2c, and malononitrile 3. After each cycle, the reaction was followed by extraction of products and catalyst. The collected catalyst was washed with acetone for several times to remove organic substances and used for the next run. The performance of the recycled catalyst was tested up to four successive runs and observed no significant loss in the reaction products (Figure 3). A plausible mechanism was suggested in Scheme 1. The reaction was supposed to continue via first Knoevenagel condensation to proceed 2-(4-hydroxy-3-methoxy-5(phenyldiazenyl)benzylidene)malononitrile (I). Consequently, the Michael addition reaction of the intermediate (II) with 1,3dicarbonyl compounds followed by tautomerization and intramolecular cyclization providing the desired product. The structures of all the products were characterized by IR, 1H NMR, 13C NMR, and mass spectrometry analysis. Further, the structure of compound 4av was confirmed by single crystal Xray diffraction method (Figure 4, CCDC-1440722). The compound 4av crystallizes in the centrosymmetric monoclinic C2/c space group with one molecule in the asymmetric unit. Table 3 gives the pertinent crystallographic data

Figure 2. XPS spectra of zirconium doped ceria nanoparticles calcined at 773 K.

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Fe3O4, ZnO, TiO2, CeO2, CeO2−ZrO2 (Table 1, entries 11− 15). However, CeO2−ZrO2 (cerium zirconium oxide) was identified as the suitable catalyst with 4ac being isolated maximum amounts (91%) and the yield of desired product was checked using different mol ratios (10, 20, 30 mol %). The maximum yield was obtained when the 20 mol % catalyst was used (Table 1, entry 16). Below this, catalyst did not yield any encouraging result and when the reaction was attempted using 30 mol %, (Table 1, entry 17) it gave good yields of 4ac. It is the same when 20 mol % used. In addition to this, we also studied the effect of temperature on the above reaction using different temperatures like 40, 50, 60 °C and reflux temperature (Table 1, entries 18−21). Among these results, we found that

EXPERIMENTAL RESULTS

Materials and Method. All reagents were procured from commercial sources and used without further purification. A Bruker WM-4 (X) spectrophotometer (577 model) was used for recording IR spectra (KBr). NMR spectra were recorded on a Bruker WM-500 spectrophotometer at 500 MHz (1H), Bruker WM-400 spectrophotometer at 400 MHz (1H), and 100 MHz (13C), respectively, in DMSO-d6 with TMS as an internal standard. Elemental analysis was performed on a Carlo Erba EA 1108 automatic elemental analyzer. Mass spectra (ESI) were carried out on a Jeol JMSD-300 spectrometer. The compound 4av was crystallized from DMF to yield prismatic crystals. XRD data was acquired in the 2θ range of 12− 80° on a Rigaku Multiflex instrument using Cu Kα (λ = 1.5418 Å) C

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ACS Sustainable Chemistry & Engineering Table 1. Effect of Solvent and Catalysts on the Synthesis of 2-Amino-4-(4-hydroxy-3-methoxy-5-((2nitrophenyldiazenyl)phenyl)-7-methyl-5-oxo-4,5-dihydropyrano[4,3-b]pyran-3-carbonitrile 4ac

entrya 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

catalyst (mol %)

solvent

temperature (°C)

time (h)

yieldb (%)

KOH (10%) triethylamine (10%) piperidine (10%) H2SO4 (10%) acetic acid (10%) Fe3O4 (10%) ZnO (10%) TiO2 (10%) CeO2 (10%) CeO2−ZrO2 (10%) CeO2−ZrO2 (20%) CeO2−ZrO2 (30%) CeO2−ZrO2 (20%) CeO2−ZrO2 (20%) CeO2−ZrO2 (20%) CeO2−ZrO2 (20%)

methanol ethanol water acetonitrile dioxane water water water water water water water water water water water water water water water water

rt rt rt rt rt rt rt rt rt rt rt rt rt rt rt rt rt 40 50 60 reflux

24 19 11 13 24 11 6 6 6 6 6 6 6 6 3 2 2 2 2 2 2

10 23 41 21 NR 41 33 39 51 46 54 59 46 71 81 91 90 80 73 51 49

a Reaction conditions: 4-hydroxy-6-methyl-2H-pyran-2-one (1 mmol), 4-hydroxy-3-methoxy-5-((2-nitrophenyl)diazenyl)benzaldehyde (1 mmol), and malononitrile (1 mmol), solvent (5 mL) and catalyst. bYields of isolated products.

radiation and a scintillation counter detector. Crystalline phases present in the samples were identified with the help of Powder Diffraction File-International Centre for Diffraction Data (PDFICDD). The average size of the crystalline domains (D) of the prepared materials were estimated with the help of the Scherrer eq 1 using the XRD data of all prominent lines. D = Kλ /β cos θ

hydrogens were generated by the riding model in idealized geometries. The software used to prepare material for publication was Mercury 2.3 (Build RC4), ORTEP-3, and X-Seed.30−32 Synthesis of 2-Amino-4-(4-hydroxy-3-methoxy-5-(substituted phenyldiazenyl)-chromene-3-carbonitrile Derivatives (4aa−4bd). A mixture of 1,3-dicarbonyl compound (1 mmol), 4hydroxy-3-methoxy-5-(substituted-phenyl diazenyl), benzaldehyde (1 mmol), and malononitrile (1 mmol) in water (5 mL) was taken in a 50 mL round-bottom flask and nano-CeO2−ZrO2 was added. The resulting mixture was stirred for 2 h at room temperature. Progress of the reaction was monitored by TLC. After completion of the reaction the product was separated from the catalyst by extracted with ethyl acetate, which was evaporated under vacuum. The product was purified by column chromatography using silica gel [ethyl acetate: nhexane (5:5)] to afford the pure compounds (4aa−4bd). 2-Amino-4-(4-hydroxy-3-methoxy-5-(phenyldiazenyl)phenyl)-7-methyl-5-oxo-4,5-dihydropyrano[4,3-b]pyran-3-carbonitrile (4aa). Dark red solid. mp 251−253 °C. IR (KBr, cm−1) vmax: 3414, 2203, 1698. 1H NMR (400 MHz, DMSO-d6): δ 2.27 (s, 3H, −CH3), 3.94 (s, 3H, −OCH3), 4.46 (s, 1H), 6.04 (s, 1H, ArH), 6.49 (s, 2H, −NH2), 7.02 (s, 1H, ArH), 7.42 (s, 1H, ArH), 7.51−7.58 (m, 3H, ArH), 7.85−7.91 (m, 2H, ArH), 10.72 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 163.57, 161.89, 158.76, 158.65, 149.71, 147.21, 146.65, 143.97, 139.20, 135.19, 134.23, 131.81, 124.83, 119.80, 119.11, 116.17, 111.86, 100.72, 98.44, 79.63, 56.68, 36.32, 19.82. ESI-MS (m/z): 429 (M − 1). Anal. calcd for C23H18N4O5: C, 64.18; H, 4.22; N, 13.02. Found: C, 64.52; H, 4.44; N, 13.38. 2-Amino-4-(4-hydroxy-3-methoxy-5-(p-tolyldiazenyl)phenyl)-7-methyl-5-oxo-4,5-dihydropyrano[4,3-b]pyran-3-carbonitrile (4ab). Red solid. mp 264−266 °C. IR (KBr, cm−1) vmax: 3398, 2201, 1707. 1H NMR (400 MHz, DMSO-d6): δ 2.23 (s, 3H,

(1)

Where D denotes the crystallite size, λ is the X-ray wavelength (1.541 Å), K indicates the particle shape factor taken as 1, β represents the peak width (fwhm, full width at half-maximum) in radians, and θ is the Bragg diffraction angle. TEM studies were made on a JEM-2010 (JEOL) instrument equipped with a slow-scan CCD camera at an accelerating voltage of 200 kV. The XPS measurements were performed on a Shimadzu (ESCA 3400) spectrometer by using Al Kα (1486.7 eV) radiation as the excitation source. Charging effects of catalyst samples were corrected by using the binding energy of the adventitious carbon (C 1s) at 284.6 eV as an internal reference. The XPS analysis was done at ambient temperature and pressures usually in the order of less than 10−8 Pa. Crystal Structure Determination. The single-crystal X-ray diffraction data of the crystals 4av were collected on a Bruker Kappa APEX-II CCD DUO diffractometer at 293(2) K using graphitemonochromated Mo Kα radiation (λ = 0.71073 Å). No absorption correction was applied. The lattice parameters were determined from least-squares analysis, and reflection data were integrated using the program SHELXTL.28 The crystal structures were solved by direct methods using SHELXS-97 and refined by full-matrix least-squares refinement on F2 with anisotropic displacement parameters for non-H atoms using SHELXL-97.29 All the aromatic and aliphatic C−H D

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Table 2. Synthesis of 2-Amino-4-(4-hydroxy-3-methoxy-5-(substituted-phenyldiazenyl)-chromene-3-carbonitrile Derivatives 4aa−bca

E

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ACS Sustainable Chemistry & Engineering Table 2. continued

a

Reaction conditions: dicarbonyl compound (1 mmol), 4-hydroxy-3-methoxy-5-((substituted phenyl)diazenyl)benzaldehyde (1 mmol) and malononitrile (1 mmol), nano-CeO2−ZrO2 (20 mol %), water (5 mL). bYields of isolated products. (t, J = 8.0 Hz, 1H, ArH), 7.73 (t, J = 8.0 Hz, 1H, ArH), 7.99 (d, J = 8.0 Hz, 1H, ArH), 8.12 (d, J = 8.0 Hz, 1H, ArH), 13.12 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 163.51, 161.90, 158.77, 158.62, 149.73, 147.20, 146.65, 143.97, 139.22, 135.19, 134.25, 131.81, 124.83, 119.80, 119.10, 116.16, 111.87, 100.72, 98.44, 79.65, 56.69, 36.34, 19.81. ESI-MS (m/z): 474 (M − 1). Anal. calcd for C23H17N5O7: C, 58.11; H, 3.60; N, 14.73. Found: C, 58.24; H, 3.43; N, 14.91. 2-Amino-4-(4-hydroxy-3-methoxy-5-((3-nitrophenyl)diazenyl)phenyl)-7-methyl-5-oxo-4,5-dihydropyrano[4,3-b]pyran-3-carbonitrile (4ad). Dark brown solid. mp 231−233 °C. IR (KBr, cm−1) vmax: 3392, 2205, 1702. 1H NMR (400 MHz, DMSO-d6): δ 2.23 (s, 3H, −CH3), 3.85 (s, 3H, −OCH3), 4.34 (s, 1H), 6.30 (s, 1H, ArH), 7.02 (s, 1H, ArH), 7.16 (s, 1H, ArH), 7.23 (s, 2H, −NH2), 7.87 (t, J = 8.0 Hz, 1H, ArH), 8.37 (d, J = 8.0 Hz, 1H, ArH), 8.46 (d, J = 8.0 Hz, 1H, ArH), 8.79 (s, 1H, ArH), 10.67 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 163.53, 161.89, 158.76, 158.62, 149.75, 147.20, 146.64, 143.98, 139.21, 135.19, 134.25, 131.81, 124.83, 119.80, 119.10, 116.14, 111.87, 100.70, 98.41, 79.64, 56.69, 36.34, 19.84. ESIMS (m/z): 474 (M − 1). Anal. calcd for C23H17N5O7: C, 58.11; H, 3.60; N, 14.73. Found: C, 58.24; H, 3.43; N, 14.91. 2-Amino-4-(4-hydroxy-3-methoxy-5-((4-nitrophenyl)diazenyl)phenyl)-7-methyl-5-oxo-4,5-dihydropyrano[4,3-b]pyran-3-carbonitrile (4ae). Dark red solid. mp 251−253 °C. IR (KBr, cm−1) vmax: 3400, 2199, 1704. 1H NMR (400 MHz, DMSO-d6): δ 2.23 (s, 3H, −CH3), 3.85 (s, 3H, −OCH3), 4.34 (s, 1H), 6.30 (s, 1H, ArH), 7.03 (s, 1H, ArH), 7.14 (s, 1H, ArH), 7.26 (s, 2H, −NH2), 8.22 (d, J = 8.0 Hz, 2H, ArH), 8.41 (d, J = 8.0 Hz, 2H, ArH), 10.76 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 163.53, 161.91, 158.77, 158.63, 149.73, 147.20, 146.64, 143.98, 139.22, 135.19, 134.25, 131.81, 124.83, 119.83, 119.14, 116.16, 111.87, 100.72, 98.44, 79.64, 56.68, 36.34, 19.83. ESI-MS (m/z): 474 (M − 1). Anal. calcd for C23H17N5O7: C, 58.11; H, 3.60; N, 14.73. Found: C, 58.24; H, 3.43; N, 14.91.

Figure 3. Reusability studies of the nanosized CeO2−ZrO2 catalyst for the synthesis of compound 4ac. −CH3), 2.41 (s, 3H, −CH3), 3.83 (s, 3H, −OCH3), 4.33 (s, 1H), 6.29 (s, 1H, ArH), 6.96 (s, 1H, ArH), 7.14 (s, 1H, ArH), 7.22 (s, 2H, −NH2), 7.38 (d, J = 8.0 Hz, 2H, ArH), 7.90 (d, J = 8.0 Hz, 2H, ArH), 10.97 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 163.42, 161.92, 158.60, 149.88, 149.29, 144.43, 142.12, 138.34, 134.90, 130.42, 123.18, 119.83, 115.06, 113.49, 100.98, 98.50, 79.42, 56.64, 36.49, 21.53, 19.82. ESI-MS (m/z): 443 (M − 1). Anal. calcd for C24H20N4O5: C, 64.86; H, 4.54; N, 12.61. Found: C, 64.92; H, 4.82; N, 12.93. 2-Amino-4-(4-hydroxy-3-methoxy-5-((2-nitrophenyl)diazenyl)phenyl)-7-methyl-5-oxo-4,5-dihydropyrano[4,3-b]pyran-3-carbonitrile (4ac). Dark red solid. mp 257−259 °C. IR (KBr, cm−1) vmax: 3394, 2200, 1714. 1H NMR (400 MHz, CDCl3-d6): δ 2.27 (s, 3H, −CH3), 3.96 (s, 3H, −OCH3), 4.52 (s, 1H), 4.73 (s, 2H, −NH2), 5.94 (s, 1H, ArH), 7.00 (s, 1H, ArH), 7.37 (s, 1H, ArH), 7.56 F

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Scheme 1. Proposed Mechanism for the Multicomponent Reaction Using Zirconium Doped Ceria Nanoparticles

Figure 4. ORTEP representation of compound 4av (CCDC-1440722). The thermal ellipsoids are drawn at 50% probability level. 2202, 1710. 1H NMR (400 MHz, DMSO-d6): δ 3.83 (s, 3H, −OCH3), 4.52 (s, 1H), 7.06 (s, 1H, ArH), 7.23 (s, 1H, ArH), 7.46 (s, 2H, −NH2), 7.46−7.59 (m, 5H, ArH), 7.73 (t, J = 8.0 Hz, 1H, ArH), 7.91 (d, J = 8.0 Hz, 1H, ArH), 7.98 (t, J = 8.0 Hz, 2H, ArH), 10.96 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 163.33, 158.37, 152.33, 148.73, 144.40, 143.42, 137.45, 134.09, 132.78, 131.28, 129.32, 124.55, 122.84, 122.46, 117.55, 116.50, 115.21, 113.13, 103.95, 78.96, 56.32, 36.81. ESI-MS (m/z): 465 (M − 1). Anal. calcd for C26H18N4O5: C, 66.95; H, 3.89; N, 12.01. Found: C, 66.67; H, 3.98; N, 12.23. 2-Amino-4-(4-hydroxy-3-methoxy-5-(p-tolyldiazenyl)phenyl)-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile (4ah). Dark red solid. mp 236−238 °C. IR (KBr, cm−1) vmax: 3373, 2204, 1714; 1H NMR (400 MHz, DMSO-d6): δ 2.40 (s, 3H, −CH3), 3.83 (s, 3H, −OCH3), 4.52 (s, 1H), 7.04 (s, 1H, ArH), 7.22 (s, 1H, ArH), 7.37 (d, J = 8.0 Hz, 2H, ArH), 7.43 (s, 2H, −NH2), 7.48 (t, J = 8.0 Hz, 1H, ArH), 7.72 (t, J = 8.0 Hz, 2H, ArH), 7.87−7.93 (m,

2-Amino-4-(3-((3-fluoro-4-morpholinophenyl)diazenyl)-4hydroxy-5-methoxyphenyl)-7-methyl-5-oxo-4,5dihydropyrano[4,3-b]pyran-3-carbonitrile (4af). Brown solid. mp 225−227 °C. IR (KBr, cm−1) vmax: 3377, 2199, 1709. 1H NMR (400 MHz, DMSO-d6): δ 2.23 (s, 3H, −CH3), 3.18−3.21 (m, 4H), 3.73− 3.90 (m, 4H), 3.96 (s, 3H, −OCH3), 4.31 (s, 1H), 6.29 (s, 1H, ArH), 6.92 (s, 1H, ArH), 7.11 (s, 1H, ArH), 7.22 (s, 2H, −NH2), 7.63 (d, J = 8.0 Hz, 1H, ArH), 7.76 (d, J = 8.0 Hz, 1H, ArH), 8.40 (s, 1H, ArH) 10.67 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 163.49, 161.92, 158.76, 158.61, 149.72, 147.20, 146.63, 143.97, 139.23, 135.19, 134.25, 131.83, 124.80, 119.82, 119.10, 116.16, 111.87, 100.72, 98.42, 79.67, 68.26, 56.68, 49.79, 36.34, 30.06, 27.68, 19.82; ESI-MS (m/z): 532 (M − 1). Anal. calcd for C27H24FN5O6: C, 60.78; H, 4.53; N, 13.13. Found: C, 60.52; H, 4.62; N, 13.22. 2-Amino-4-(4-hydroxy-3-methoxy-5-(phenyldiazenyl)phenyl)-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile (4ag). Red solid. mp 240−242 °C. IR (KBr, cm−1) vmax: 3373, G

DOI: 10.1021/acssuschemeng.6b00056 ACS Sustainable Chem. Eng. XXXX, XXX, XXX−XXX

Research Article

ACS Sustainable Chemistry & Engineering

carbonitrile (4ak). Dark red solid. mp 228−230 °C. IR (KBr, cm−1) vmax: 3358, 2205, 1718. 1H NMR (400 MHz, DMSO-d6): δ 3.84 (s, 3H, −OCH3), 4.52 (s, 1H), 7.11 (s, 1H, ArH), 7.22 (s, 1H, ArH), 7.47 (s, 2H, −NH2), 7.51 (t, J = 8.0 Hz, 1H, ArH), 7.73 (t, J = 8.0 Hz, 1H, ArH), 7.93 (t, J = 8.0 Hz, 2H, ArH), 8.21 (d, J = 8.0 Hz, 2H, ArH), 8.40 (d, J = 8.0 Hz, 2H, ArH), 10.79 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 162.80, 160.13, 158.52, 155.50, 153.94, 152.66, 149.88, 148.62, 146.91, 139.18, 134.74, 133.47, 125.37, 125.17, 124.24, 123.06, 119.71, 117.09, 116.38, 113.53, 110.87, 104.03, 79.65, 56.72, 36.28. ESI-MS (m/z): 510 (M − 1). Anal. calcd for C26H17N5O7: C, 61.06; H, 3.35; N, 13.69. Found: C, 61.32; H, 3.43; N, 13.90. 2-Amino-4-(3-((3-fluoro-4-morpholinophenyl)diazenyl)-4hydroxy-5-methoxyphenyl)-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile (4al). Brown solid. mp 220−222 °C. IR (KBr, cm−1) vmax: 3411, 2227, 1731. 1H NMR (400 MHz, DMSO-d6): δ 3.16−3.21 (m, 4H), 3.76−3.79 (m, 4H), 3.96 (s, 3H, −OCH3), 4.48 (s, 1H), 7.19−7.24 (m, 3H, ArH), 7.42 (s, 2H, −NH2), 7.57 (s, 1H, ArH), 7.62 (d, J = 8.0 Hz, 1H, ArH), 7.76 (d, J = 8.0 Hz, 1H, ArH), 7.84 (s, 1H, ArH), 7.90 (d, J = 8.0 Hz, 1H, ArH), 8.01 (d, J = 8.0 Hz, 1H, ArH), 11.03 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 163.15, 156.12, 153.50, 152.20, 150.06, 148.91, 146.59, 144.09, 142.74, 140.22, 139.30, 134.38, 130.43, 128.29, 126.75, 124.20, 122.25, 118.61, 115.06, 110.65, 108.10, 104.92, 78.63, 66.03, 56.04, 50.00, 37.37. ESIMS (m/z): 568 (M − 1). Anal. calcd for C30H24FN5O6: C, 63.27; H, 4.25; N, 12.30. Found: C, 63.52; H, 4.33; N, 12.57. 2-Amino-4-(4-hydroxy-3-methoxy-5-(phenyldiazenyl)phenyl)-5,10-dioxo-5,10-dihydro-4H-benzo[g]chromene-3-carbonitrile (4am). Red solid. mp 265−267 °C. IR (KBr, cm−1) vmax: 3453, 2190, 1723, 1657. 1H NMR (400 MHz, DMSO-d6): δ 3.84 (s, 3H, −OCH3), 4.67 (s, 1H), 7.07 (s, 1H, ArH), 7.30 (s, 1H, ArH), 7.35 (s, 2H, −NH2), 7.54−7.59 (m, 3H, ArH), 7.83−7.87 (m, 2H, ArH), 7.89−7.92 (m, 1H, ArH), 7.97−8.00 (m, 2H, ArH), 8.04−8.08 (m, 1H, ArH), 10.97 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 183.21, 177.41, 158.87, 151.84, 149.57, 149.34, 144.75, 138.43, 134.98, 134.91, 134.59, 131.83, 131.57, 131.18, 129.88, 126.52, 126.31, 123.17, 121.96, 119.88, 115.39, 113.86, 79.65, 56.76, 36.85. ESI-MS (m/z): 477 (M − 1). Anal. calcd for C27H18N4O5: C, 67.78; H, 3.79; N, 11.71. Found: C, 67.51; H, 3.50; N, 11.93. 2-Amino-4-(4-hydroxy-3-methoxy-5-(p-tolyldiazenyl)phenyl)-5,10-dioxo-5,10-dihydro-4H-benzo[g]chromene-3-carbonitrile (4an). Red solid. mp 271−273 °C. IR (KBr, cm−1) vmax: 3389, 2201, 1721, 1667. 1H NMR (400 MHz, DMSO-d6): δ 2.40 (s, 3H, −CH3), 3.84 (s, 3H, −OCH3), 4.66 (s, 1H), 7.06 (s, 1H, ArH), 7.29 (s, 1H, ArH), 7.35 (s, 2H, −NH2), 7.38 (d, J = 8.0 Hz, 1H, ArH), 7.83−7.91 (m, 6H, ArH), 8.04−8.07 (m, 1H, ArH), 11.05 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 183.81, 177.63, 158.97, 151.98, 150.80, 149.73, 144.97, 138.83, 135.76, 134.93, 134.40, 132.40, 132.01, 130.60, 129.56, 126.80, 126.39, 123.22, 121.84, 119.36, 115.85, 113.04, 79.74, 56.41, 36.54, 20.30. ESI-MS (m/z): 491 (M − 1). Anal. calcd for C28H20N4O5: C, 68.29; H, 4.09; N, 11.38. Found: C, 68.52; H, 4.14; N, 11.09. 2-Amino-4-(4-hydroxy-3-methoxy-5-((2-nitrophenyl)diazenyl)phenyl)-5,10-dioxo-5,10-dihydro-4H-benzo[g]chromene-3-carbonitrile (4ao). Red solid. mp 251−253 °C. IR (KBr, cm−1) vmax: 3453, 2190, 1722, 1655. 1H NMR (400 MHz, DMSO-d6): δ 3.84 (s, 3H, −OCH3), 4.66 (s, 1H), 7.07 (s, 1H, ArH), 7.30 (s, 1H, ArH), 7.36 (s, 2H, −NH2), 7.54−7.60 (m, 2H, ArH), 7.81−7.85 (m, 2H, ArH), 7.88−7.91 (m, 1H, ArH), 7.98 (d, J = 8.0 Hz, 2H, ArH), 8.04−8.08 (m, 1H, ArH), 10.96 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 183.21, 177.42, 158.87, 151.84, 149.57, 149.34, 144.74, 138.43, 134.99, 134.91, 134.59, 131.83, 131.57, 131.18, 129.89, 126.53, 126.32, 123.17, 121.97, 119.88, 115.39, 113.86, 79.65, 56.76, 36.84. ESI-MS (m/z): 522 (M − 1). Anal. calcd for C27H17N5O7: C, 61.95; H, 3.27; N, 13.38. Found: C, 61.82; H, 3.33; N, 13.21. 2-Amino-4-(4-hydroxy-3-methoxy-5-((3-nitrophenyl)diazenyl)phenyl)-5,10-dioxo-5,10-dihydro-4H-benzo[g]chromene-3-carbonitrile (4ap). Brown solid. mp 244−246 °C. IR (KBr, cm−1) vmax: 3455, 2194, 1728, 1657. 1H NMR (400 MHz, DMSO-d6): δ 3.84 (s, 3H, −OCH3), 4.66 (s, 1H), 7.08 (s, 1H, ArH), 7.30 (s, 1H, ArH), 7.41 (s, 2H, −NH2), 7.57−7.64 (m, 2H, ArH), 7.72

Table 3. Salient Crystallographic Data and Structure Refinement Parameters of Compound 4av 4av empirical formula formula weight crystal system space group T/K a/Å b/Å c/Å α/deg β/deg γ/deg Z V/Å3 Dcalc/Mg/cm3 F(000) μ/mm−1 θ/deg index ranges

N-total N-independent parameters R1 (I > 2σ(I)) wR2 (all data) GOF CCDC

C28H29N6O7 561.57 monoclinic C2/c 296(2) 13.5896(13) 15.1701(14) 27.316(3) 90 92.580(4) 90 8 5625.7(9) 1.326 2360 0.097 1.49−28.33 −18 ≤ h ≤ 18 −16 ≤ k ≤ 20 −36 ≤ l ≤ 36 23076 6949 373 0.0508 0.2159 1.017 1440722

3H, ArH), 11.03 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 163.80, 158.32, 152.75, 148.10, 144.89, 143.47, 137.97, 134.77, 132.47, 131.28, 129.51, 123.45, 123.13, 122.27, 117.93, 116.79, 115.00, 103.10, 78.73, 57.27, 49.09, 36.94, 19.77. ESI-MS (m/z): 479 (M − 1). Anal. calcd for C27H20N4O5: C, 67.49; H, 4.20; N, 11.66. Found: C, 67.80; H, 4.01; N, 11.83. 2-Amino-4-(4-hydroxy-3-methoxy-5-((2-nitrophenyl)diazenyl)phenyl)-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3carbonitrile (4ai). Red solid. mp 231−233 °C. IR (KBr, cm−1) vmax: 3381, 2200, 1717. 1H NMR (500 MHz, DMSO-d6): δ 3.84 (s, 3H, −OCH3), 4.50 (s, 1H), 7.10 (s, 1H, ArH), 7.44 (s, 2H, −NH2), 7.47− 7.52 (m, 2H, ArH), 7.73 (t, J = 10.0 Hz, 2H, ArH), 7.83 (t, J = 10.0 Hz, 1H, ArH), 7.91−7.97 (m, 3H, ArH), 8.10 (d, J = 10.0 Hz, 1H, ArH), 10.98 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 162.83, 160.93, 159.75, 157.46, 152.17, 149.79, 148.73, 146.21, 141.52, 138.37, 134.40, 132.33, 125.93, 125.01, 123.93, 122.15, 115.83, 114.48, 109.55, 106.03, 103.54, 76.96, 56.56, 36.18. ESI-MS (m/z): 510 (M − 1). Anal. calcd for C26H17N5O7: C, 61.06; H, 3.35; N, 13.69. Found: C, 61.32; H, 3.43; N, 13.90. 2-Amino-4-(4-hydroxy-3-methoxy-5-((3-nitrophenyl)diazenyl)phenyl)-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3carbonitrile (4aj). Brown solid. mp 248−250 °C. IR (KBr, cm−1) vmax: 3327, 2185, 1723. 1H NMR (500 MHz, DMSO-d6): δ 3.84 (s, 3H, −OCH3), 4.51 (s, 1H), 7.08 (s, 1H, ArH), 7.24 (s, 1H, ArH), 7.45 (s, 2H, −NH2), 7.46−7.52 (m, 2H, ArH), 7.72 (t, J = 10.0 Hz, 1H, ArH), 7.85 (t, J = 10.0 Hz, 1H, ArH), 7.90−7.96 (m, 2H, ArH), 8.35 (d, J = 10.0 Hz, 1H, ArH), 8.78 (s, 1H, ArH), 10.69 (s, 1H, −OH). 13 C NMR (100 MHz, DMSO-d6): δ 162.36, 160.66, 159.69, 157.30, 152.23, 149.55, 148.79, 146.09, 141.88, 138.39, 134.18, 132.99, 125.72, 125.04, 123.52, 122.05, 115.88, 114.55, 110.28, 106.07, 103.74, 77.68, 56.11, 36.83. ESI-MS (m/z): 510 (M − 1). Anal. calcd for C26H17N5O7: C, 61.06; H, 3.35; N, 13.69. Found: C, 61.31; H, 3.44; N, 13.88. 2-Amino-4-(4-hydroxy-3-methoxy-5-((4-nitrophenyl)diazenyl)phenyl)-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3H

DOI: 10.1021/acssuschemeng.6b00056 ACS Sustainable Chem. Eng. XXXX, XXX, XXX−XXX

Research Article

ACS Sustainable Chemistry & Engineering (s, 2H, ArH), 7.81−7.85 (m, 1H, ArH), 7.90 (d, J = 8.0 Hz, 2H, ArH), 7.95−7.99 (m, 1H, ArH), 11.05 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 183.75, 177.74, 159.00, 151.87, 149.81, 144.05, 138.04, 135.76, 135.18, 133.71, 131.70, 131.43, 129.69, 127.41, 126.52, 123.66, 121.07, 119.65, 115.65, 113.65, 79.95, 57.00, 36.60. ESI-MS (m/z): 522 (M − 1). Anal. calcd for C27H17N5O7: C, 61.95; H, 3.27; N, 13.38. Found: C, 61.80; H, 3.31; N, 13.22. 2-Amino-4-(4-hydroxy-3-methoxy-5-((4-nitrophenyl)diazenyl)phenyl)-5,10-dioxo-5,10-dihydro-4H-benzo[g]chromene-3-carbonitrile (4aq). Brown solid. mp 260−262 °C. IR (KBr, cm−1) vmax: 3454, 2198, 1723, 1653; 1H NMR (400 MHz, DMSO-d6): δ 3.92 (s, 3H, −OCH3), 4.66 (s, 1H), 7.08 (s, 1H, ArH), 7.31 (s, 1H, ArH), 7.43 (s, 2H, −NH2), 7.78 (d, 1H, J = 8.0 Hz, ArH), 8.02 (d, 1H, J = 8.0 Hz, ArH), 8.20 (d, 2H, J = 8.0 Hz, ArH), 8.42− 8.47 (m, 4H, ArH), 11.02 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 183.10, 177.07, 158.68, 152.28, 150.69, 149.68, 144.96, 140.63, 138.34, 136.26, 134.33, 133.73, 132.46, 126.25, 125.69, 125.52, 125.34, 123.88, 118.27, 115.87, 113.52, 79.40, 56.40, 36.38. ESI-MS (m/z): 522 (M − 1). Anal. calcd for C27H17N5O7: C, 61.95; H, 3.27; N, 13.38. Found: C, 61.80; H, 3.35; N, 13.19. 2-Amino-4-(3-((3-fluoro-4-morpholinophenyl)diazenyl)-4hydroxy-5-methoxyphenyl)-5,10-dioxo-5,10-dihydro-4Hbenzo[g]chromene-3-carbonitrile (4ar). Brown solid. mp 242− 244 °C. IR (KBr, cm−1) vmax: 3443, 2197, 1721, 1657. 1H NMR (400 MHz, DMSO-d6): δ 3.10−3.16 (m, 4H), 3.76−3.79 (m, 4H), 3.91 (s, 3H, −OCH3), 4.65 (s, 1H), 7.77 (s, 1H, ArH), 7.89−7.91 (m, 3H, ArH), 8.01 (s, 1H, ArH), 8.31 (s, 2H, −NH2), 8.38−8.46 (m, 3H, ArH), 8.79 (s, 1H, ArH), 10.75 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 183.77, 177.37, 161.24, 156.29, 153.84, 152.09, 150.10, 146.73, 143.18, 139.16, 134.87, 132.10, 129.90, 127.70, 124.88, 122.63, 118.83, 116.15, 115.27, 114.26, 110.71, 106.81, 104.17, 79.65, 66.48, 56.53, 50.42, 36.35. ESI-MS (m/z): 580 (M − 1). Anal. calcd for C31H24FN5O6: C, 64.02; H, 4.16; N, 12.04. Found: C, 64.32; H, 4.01; N, 12.21. 2-Amino-4-(4-hydroxy-3-methoxy-5-(phenyldiazenyl)phenyl)-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene3-carbonitrile (4as). Red solid. mp 246−248 °C. IR (KBr, cm−1) vmax: 3452, 2190, 1676. 1H NMR (400 MHz, DMSO-d6): δ 1.02 (s, 3H, −CH3), 1.06 (s, 3H, −CH3), 2.09−2.33 (m, 4H), 3.83 (s, 3H, −OCH3), 4.21 (s, 1H), 6.90 (s, 1H, ArH), 7.03 (s, 2H, −NH2), 7.11 (s, 1H, ArH), 7.54−7.61 (m, 3H, ArH), 7.97 (d, J = 8.0 Hz, 2H, ArH), 10.74 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 196.29, 163.23, 158.95, 151.96, 149.44, 144.68, 138.65, 136.00, 131.76, 129.88, 123.17, 120.26, 114.72, 112.89, 111.92, 56.59, 50.48, 35.64, 32.28, 29.17, 26.96. ESI-MS (m/z): 443 (M − 1). Anal. calcd for C25H24N4O4: C, 67.55; H, 5.44; N, 12.60. Found: C, 67.41; H, 5.32; N, 12.82. 2-Amino-4-(4-hydroxy-3-methoxy-5-(p-tolyldiazenyl)phenyl)-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene3-carbonitrile (4at). Yellow solid. mp 247−249 °C. IR (KBr, cm−1) vmax: 3437, 2189, 1735. 1H NMR (400 MHz, DMSO-d6): δ 1.01 (s, 3H, −CH3), 1.06 (s, 3H, −CH3), 2.09−2.31 (m, 2H), 2.41 (s, 3H, −CH3), 2.52−2.73 (m, 2H), 3.82 (s, 3H, −OCH3), 4.21 (s, 1H), 6.88 (s, 1H, ArH), 7.02 (s, 2H, −NH2), 7.11 (s, 1H, ArH), 7.39 (d, J = 8.0 Hz, 2H, ArH), 7.88 (d, J = 8.0 Hz, 2H, ArH), 10.80 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 196.00, 162.87, 158.60, 149.63, 148.99, 143.94, 142.26, 141.73, 138.16, 135.60, 130.07, 122.79, 119.90, 114.14, 112.56, 112.01, 79.27, 56.23, 50.13, 35.27, 31.93, 28.78, 26.62, 21.17. ESI-MS (m/z): 457 (M − 1). Anal. calcd for C26H26N4O4: C, 68.11; H, 5.72; N, 12.22. Found: C, 68.32; H, 5.81; N, 12.46. 2-Amino-4-(4-hydroxy-3-methoxy-5-((2-nitrophenyl)diazenyl)phenyl)-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4Hchromene-3-carbonitrile (4au). Dark red solid. mp 231−233 °C. IR (KBr, cm−1) vmax: 3498, 2190, 1678. 1H NMR (400 MHz, DMSOd6): δ 0.99 (s, 3H, −CH3), 1.06 (s, 3H, −CH3), 2.09−2.32 (m, 2H), 2.57−2.89 (m, 2H), 3.85 (s, 3H, −OCH3), 4.18 (s, 1H), 6.94 (s, 1H, ArH), 6.96 (s, 1H, ArH), 7.04 (s, 2H, −NH2), 7.74 (t, J = 8.0 Hz, 1H, ArH), 7.85 (t, J = 8.0 Hz, 1H, ArH), 7.97 (d, J = 8.0 Hz, 1H, ArH), 8.11 (d, J = 8.0 Hz, 1H, ArH), 10.73 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 196.58, 163.56, 159.17, 149.98, 147.67, 146.85, 139.75, 136.59, 134.43, 132.02, 124.96, 120.43, 119.33, 116.07, 112.96,

110.56, 79.88, 56.92, 50.73, 35.83, 32.48, 29.32, 27.37. ESI-MS (m/z): 488 (M − 1). Anal. calcd for C25H23N5O6: C, 61.34; H, 4.74; N, 14.31. Found: C, 61.41; H, 4.51; N, 14.43. 2-Amino-4-(4-hydroxy-3-methoxy-5-((3-nitrophenyl)diazenyl)phenyl)-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4Hchromene-3-carbonitrile (4av). Red solid. mp 249−251 °C. IR (KBr, cm−1) vmax: 3400, 2187, 1680. 1H NMR (400 MHz, DMSO-d6): δ 1.03 (s, 3H, −CH3), 1.06 (s, 3H, −CH3), 2.10−2.32 (m, 2H), 2.53− 2.61 (m, 2H), 3.84 (s, 3H, −OCH3), 4.20 (s, 1H), 6.93 (s, 1H, ArH), 7.05 (s, 2H, −NH2), 7.12 (s, 1H, ArH), 7.88 (t, J = 8.0 Hz, 1H, ArH), 8.36 (d, J = 8.0 Hz, 1H, ArH), 8.44 (d, J = 8.0 Hz, 1H, ArH), 8.78 (s, 1H, ArH), 10.58 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 195.84, 162.86, 158.48, 152.29, 149.35, 148.81, 145.95, 138.52, 135.56, 133.27, 130.90, 130.44, 125.02, 119.78, 116.30, 115.86, 114.89, 112.30, 108.51, 104.94, 102.72, 56.07, 49.98, 35.17, 31.82, 28.74, 26.43. ESIMS (m/z): 488 (M − 1). Anal. calcd for C25H23N5O6: C, 61.34; H, 4.74; N, 14.31. Found: C, 61.39; H, 4.54; N, 14.49. 2-Amino-4-(4-hydroxy-3-methoxy-5-((4-nitrophenyl)diazenyl)phenyl)-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4Hchromene-3-carbonitrile (4aw). Dark red solid. mp 244−246 °C. IR (KBr, cm−1) vmax: 3371, 2183, 1678. 1H NMR (400 MHz, DMSOd6): δ 1.02 (s, 3H, −CH3), 1.06 (s, 3H, −CH3), 2.09−2.33 (m, 2H), 2.57−2.68 (m, 2H), 3.84 (s, 3H, −OCH3), 4.21 (s, 1H), 6.95 (s, 1H, ArH), 7.04 (s, 2H, −NH2), 7.11 (s, 1H, ArH), 8.20 (d, J = 8.0 Hz, 2H, ArH), 8.41 (d, J = 8.0 Hz, 2H, ArH), 10.65 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 195.76, 162.79, 158.47, 155.05, 149.33, 148.12, 146.24, 138.81, 136.63, 135.62, 124.90, 123.68, 119.69, 115.26, 112.27, 109.03, 56.09, 35.14, 31.77, 28.66, 26.43. ESI-MS (m/z): 488 (M − 1). Anal. calcd for C25H23N5O6: C, 61.34; H, 4.74; N, 14.31. Found: C, 61.40; H, 4.52; N, 14.41. 2-Amino-4-(3-((3-fluoro-4-morpholinophenyl)diazenyl)-4hydroxy-5-methoxyphenyl)-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile (4ax). Brown solid. mp 236− 238 °C. IR (KBr, cm−1) vmax: 3373, 2187, 1677. 1H NMR (400 MHz, DMSO-d6): δ 1.01 (s, 3H, −CH3), 1.05 (s, 3H, −CH3), 2.09−2.31 (m, 2H), 2.56−2.89 (m, 2H), 3.17−3.21 (m, 4H), 3.72−3.81 (m, 4H), 3.96 (s, 3H, −OCH3), 4.18 (s, 1H), 6.84 (s, 1H, ArH), 7.03 (s, 2H, −NH2), 7.07 (s, 1H, ArH), 7.64 (d, J = 8.0 Hz, 1H, ArH), 7.75 (d, J = 8.0 Hz, 1H, ArH), 8.41 (s, 1H, ArH), 10.48 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 195.75, 162.69, 158.42, 155.95, 148.93, 144.28, 138.07, 135.39, 128.25, 124.67, 123.34, 122.16, 119.74, 118.36, 113.84, 112.40, 110.20, 77.96, 66.00, 56.02, 49.97, 35.16, 31.75, 28.67, 26.43. ESI-MS (m/z): 546 (M − 1). Anal. calcd for C29H30FN5O5: C, 63.61; H, 5.52; N, 12.79. Found: C, 63.42; H, 5.71; N, 12.61. 2-Amino-4-(4-hydroxy-3-methoxy-5-(phenyldiazenyl)phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile (4ay). Dark red solid. mp 206−208 °C. IR (KBr, cm−1) vmax: 3402, 2194, 1665. 1H NMR (400 MHz, DMSO-d6): δ 1.88−2.01 (m, 2H), 2.27−2.33 (m, 2H), 2.60−2.67 (m, 2H), 3.84 (s, 3H, −OCH3), 4.24 (s, 1H), 6.92 (s, 1H, ArH), 7.06 (s, 2H, −NH2), 7.13 (s, 1H, ArH), 7.55−7.60 (m, 3H, ArH), 7.92−8.06 (m, 2H, ArH), 10.91 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 196.00, 164.49, 162.30, 158.54, 151.34, 148.85, 143.89, 137.94, 135.54, 131.27, 129.38, 122.96, 122.64, 119.79, 114.52, 113.56, 112.60, 56.14, 36.39, 35.11, 26.51, 19.84. ESI-MS (m/z): 415 (M − 1). Anal. calcd for C23H20N4O4: C, 66.34; H, 4.84; N, 13.45. Found: C, 66.57; H, 4.62; N, 13.61. 2-Amino-4-(4-hydroxy-3-methoxy-5-(p-tolyldiazenyl)phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile (4az). Red solid. mp 249−251 °C. IR (KBr, cm−1) vmax: 3405, 2194, 1681. 1H NMR (400 MHz, DMSO-d6): δ 1.90−2.00 (m, 2H), 2.29− 2.33 (m, 2H), 2.41 (s, 3H, −CH3), 2.60−2.69 (m, 2H), 3.83 (s, 3H, −OCH3), 4.23 (s, 1H), 6.90 (s, 1H, ArH), 7.04 (s, 2H, −NH2), 7.13 (s, 1H, ArH), 7.39 (d, J = 8.0 Hz, 2H, ArH), 7.90 (d, J = 8.0 Hz, 2H, ArH), 10.98 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 196.01, 164.47, 158.54, 149.35, 148.75, 143.55, 141.59, 137.78, 135.50, 129.93, 122.64, 119.79, 114.29, 113.59, 113.01, 56.12, 36.38, 35.09, 26.50, 21.02, 19.84. ESI-MS (m/z): 429 (M − 1). Anal. calcd for C24H22N4O4: C, 66.97; H, 5.15; N, 13.02. Found: C, 67.12; H, 5.44; N, 13.23. 2-Amino-4-(4-hydroxy-3-methoxy-5-((2-nitrophenyl)diazenyl)phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3I

DOI: 10.1021/acssuschemeng.6b00056 ACS Sustainable Chem. Eng. XXXX, XXX, XXX−XXX

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carbonitrile (4ba). Dark red solid. mp 239−241 °C. IR (KBr, cm−1) vmax: 3397, 2190, 1677. 1H NMR (400 MHz, DMSO-d6): δ 1.92−2.03 (m, 2H), 2.25−2.37 (m, 2H), 2.60−2.65 (m, 2H), 3.86 (s, 3H, −OCH3), 4.21 (s, 1H), 6.97 (s, 1H, ArH), 6.98 (s, 1H, ArH), 7.03 (s, 2H, −NH2), 7.74 (t, J = 8.0 Hz, 1H, ArH), 7.85 (t, J = 8.0 Hz, 1H, ArH), 8.00 (d, J = 8.0 Hz, 1H, ArH), 8.12 (d, J = 8.0 Hz, 1H, ArH), 10.82 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 196.53, 165.07, 159.02, 152.68, 149.72, 149.25, 146.13, 138.82, 136.05, 131.33, 130.78, 125.45, 120.27, 116.42, 115.63, 113.94, 109.95, 79.65, 56.59, 36.89, 35.65, 27.03, 20.35. ESI-MS (m/z): 460 (M − 1). Anal. calcd for C23H19N5O6: C, 59.87; H, 4.15; N, 15.18. Found: C, 60.12; H, 4.31; N, 14.99. 2-Amino-4-(4-hydroxy-3-methoxy-5-((3-nitrophenyl)diazenyl)phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3carbonitrile (4bb). Yellow solid. mp 247−249 °C. IR (KBr, cm−1) vmax: 3402, 2194, 1677. 1H NMR (400 MHz, DMSO-d6): δ 1.92−2.00 (m, 2H), 2.29−2.33 (m, 2H), 2.61−2.68 (m, 2H), 3.85 (s, 3H, −OCH3), 4.23 (s, 1H), 6.95 (s, 1H, ArH), 7.05 (s, 2H, −NH2), 7.15 (s, 1H, ArH), 7.88 (t, J = 8.0 Hz, 1H, ArH), 8.37 (d, J = 8.0 Hz, 1H, ArH), 8.47 (d, J = 8.0 Hz, 1H, ArH), 8.79 (s, 1H, ArH), 10.64 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 196.13, 165.36, 159.60, 152.44, 150.14, 149.54, 146.98, 138.63, 136.03, 131.11, 130.01, 125.45, 120.23, 116.75, 115.65, 113.07, 109.29, 79.95, 56.41, 36.60, 34.85, 27.39, 20.46. ESI-MS (m/z): 460 (M − 1). Anal. calcd for C23H19N5O6: C, 59.87; H, 4.15; N, 15.18. Found: C, 59.73; H, 4.30; N, 15.25. 2-Amino-4-(4-hydroxy-3-methoxy-5-((4-nitrophenyl)diazenyl)phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3carbonitrile (4bc). Red solid. mp 253−255 °C. IR (KBr, cm−1) vmax: 3411, 2191, 1667. 1H NMR (400 MHz, DMSO-d6): δ 1.89−2.02 (m, 2H), 2.26−2.33 (m, 2H), 2.61−2.69 (m, 2H), 3.86 (s, 3H, −OCH3), 4.24 (s, 1H), 6.97 (s, 1H, ArH), 7.05 (s, 2H, −NH2), 7.13 (s, 1H, ArH), 7.22 (d, J = 8.0 Hz, 2H, ArH), 7.41 (d, J = 8.0 Hz, 2H, ArH), 10.75 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 196.56, 165.59, 159.69, 152.79, 150.31, 149.68, 146.21, 138.78, 136.87, 132.14, 130.34, 125.31, 120.60, 116.87, 115.00, 113.43, 109.34, 80.00, 56.83, 36.81, 34.66, 27.14, 20.30. ESI-MS (m/z): 460 (M − 1). Anal. calcd for C23H19N5O6: C, 59.87; H, 4.15; N, 15.18. Found: C, 59.78; H, 4.27; N, 15.31. 2-Amino-4-(3-((3-fluoro-4-morpholinophenyl)diazenyl)-4hydroxy-5-methoxyphenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile (4bd). Dark red solid. mp 241−243 °C. IR (KBr, cm−1) vmax: 3409, 2197, 1669. 1H NMR (400 MHz, DMSO-d6): δ 1.91−1.97 (m, 2H), 2.28−2.32 (m, 2H), 2.60−2.65 (m, 2H), 3.17− 3.21 (m, 4H), 3.72−3.78 (m, 4H), 3.95 (s, 3H, −OCH3), 4.20 (s, 1H), 6.86 (s, 1H, ArH), 7.04 (s, 2H, −NH2), 7.09 (s, 1H, ArH), 7.64 (d, J = 8.0 Hz, 1H, ArH), 7.75 (d, J = 8.0 Hz, 1H, ArH), 8.03 (s, 1H, ArH), 10.75 (s, 1H, −OH). 13C NMR (100 MHz, DMSO-d6): δ 196.36, 166.77, 164.53, 158.51, 150.07, 148.89, 142.28, 137.90, 135.45, 132.52, 130.78, 123.35, 122.25, 118.40, 115.78, 113.56, 111.01, 79.30, 66.04, 56.05, 50.02, 36.41, 35.18, 26.54, 19.88. ESI-MS (m/z): 518 (M − 1). Anal. calcd for C27H26FN5O5: C, 62.42; H, 5.04; N, 13.48. Found: C, 62.73; H, 5.37; N, 13.21.

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Research Article

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acssuschemeng.6b00056. Copies of 1H, 13C NMR, and mass spectra of the obtained compounds (PDF)

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AUTHOR INFORMATION

Corresponding Author

*Tel.: +91-870-246-2660. Fax: +91-870-245-9547. E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The authors are thankful to the Director, National Institute of Technology, Warangal, for providing facilities. One of the authors PSVK also grateful to council of scientific & industrial research (CSIR), New Delhi [File no. 09/922 (0005)2012/ EMR-I], India, for the award of senior research fellowship. We are also thankful to STIC Cochin for single crystal X-ray diffraction facility.

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REFERENCES

(1) Ekins, S.; Clark, A. M.; Williams, A. J. Incorporating Green Chemistry Concepts into Mobile Chemistry Applications and Their Potential Uses. ACS Sustainable Chem. Eng. 2013, 1, 8−13. (2) Jiang, Z.; et al. Metal-Oxide-Catalyzed Efficient Conversion of Cellulose to Oxalic Acid in Alkaline Solution under Low Oxygen Pressure. ACS Sustainable Chem. Eng. 2016, 4, 305−311. (3) Bazgir, A.; Hosseini, G.; Ghahremanzadeh, R. Copper Ferrite Nanoparticles: An Efficient and Reusable Nanocatalyst for a Green One-Pot, Three-component Synthesis of Spirooxindoles in Water. ACS Comb. Sci. 2013, 15, 530−534. (4) Call, F.; Roeb, M.; Schmücker, M.; Sattler, C.; Pitz-Paal, R. J. Phys. Chem. C 2015, 119, 6929−6938. (5) Vinodkumar, T.; Naga Durgasri, D.; Reddy, B. M.; Alxneit, I. Catal. Lett. 2014, 144, 2033−2042. (6) Patel, M.; Jindal, T. K.; Pant, K. K. Ind. Eng. Chem. Res. 2013, 52, 15763−15771. (7) Gholinejad, M.; Jeddi, N. Copper Nanoparticles Supported on Agarose as a Bioorganic and Degradable Polymer for Multicomponent Click Synthesis of 1,2,3-Triazoles under Low Copper Loading in Water. ACS Sustainable Chem. Eng. 2014, 2, 2658−2665. (8) Rotstein, S. Z.; et al. Small heterocycles in multicomponent reactions. Chem. Rev. 2014, 114, 8323−8359. (9) Brahmachari, G.; Banerjee, B. Facile and One-Pot Access to Diverse and Densely Functionalized 2-Amino-3-cyano-4H-pyrans and Pyran-Annulated Heterocyclic Scaffolds via an Eco-Friendly Multicomponent Reaction at Room Temperature Using Urea as a Novel Organo-Catalyst. ACS Sustainable Chem. Eng. 2014, 2, 411−422. (10) Zhang, Y.; et al. On water” direct catalytic vinylogous Henry (nitroaldol) reactions of isatins for the efficient synthesis of isoxazole substituted 3-hydroxyindolin-2-ones. Green Chem. 2015, 17, 3266− 3270. (11) Kalaria, P. N.; Satasia, S. P.; Raval, D. K. Synthesis, identification and in vitro biological evaluation of some novel 5-imidazopyrazole incorporated pyrazoline and isoxazoline derivatives. New J. Chem. 2014, 38, 1512−1521. (12) Gudipudi, G.; Sagurthi, S. R.; Perugu, S.; Achaiah, G.; Krupadanam, G. L. D. Rational design and synthesis of novel 2(substituted-2H-chromen-3-yl)-5-aryl-1H-imidazole derivatives as an anti-angiogenesis and anti-cancer agent. RSC Adv. 2014, 4, 56489− 56501.

CONCLUSION

In summary, an efficient and one-pot multicomponent reaction in aqueous medium using zirconium doped ceria nanoparticles acting as heterogeneous catalyst has been developed for the synthesis of a novel phenyldiazenyl-chromene derivatives by starting with 1,3-dicarbonyl compounds, 4-hydroxy-3-methoxy5-(substituted-phenyl diazenyl) benzaldehydes, and malononitrile. This protocol has the advantages of a wide scope of operational simplicity, ease separation, easy of handling, high catalytic activity, and reusability of the catalyst. J

DOI: 10.1021/acssuschemeng.6b00056 ACS Sustainable Chem. Eng. XXXX, XXX, XXX−XXX

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ACS Sustainable Chemistry & Engineering

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DOI: 10.1021/acssuschemeng.6b00056 ACS Sustainable Chem. Eng. XXXX, XXX, XXX−XXX